DNA and RNA Bases. In DNA, there are four different bases: adenine (A) and guanine (G) are the larger purines. Cytosine (C) and thymine (T) are the smaller pyrimidines.
Gretna is the second-largest city and parish seat of Jefferson Parish, Louisiana, United States. Gretna is on the west bank of the Mississippi River, just east and across the river from uptown New Orleans. It is part of the New Orleans â Metairie â Kenner Metropolitan Statistical Area. The population was 17,736 at the 2010 census.
On 6/25/1977, a category F2 tornado 6.3 miles away from the town center caused between $5000 and $50,000 in damages. Gretna-area historical earthquake activity is near Virginia state average.